Selective absorber coatings based on tellurium pigments

Selective absorber surfaces with extremely high absorptivity/emissivity ratios combined with very high (97%) absorptivities can be produced using textured tellurium coatings over polished metal surfaces. Such coatings have many of the mechanical properties of soot, however, and their practical application in this form is therefore difficult. A study has now been made in which these textured tellurium coatings have themselves been sprayed with a silicone binder to produce adherent paint-like coatings on polished copper substrates. Such coatings can have absorptivity/emissivity ratios from 6/1 to more than 20/1 depending upon the mass of binder applied per unit area. However, adherence is significantly compromised for binder levels less than 50 μg/cm². © 1985.